Multi-material thermal barrier coating system

Abstract

The thermal barrier coating system comprises a matrix of a first chemistry with multiple embedded second phases of a second chemistry. The matrix comprises a stabilized zirconia. The second regions comprise at least 40 mole percent of oxides having the formula Ln 2 O 3 , where Ln is selected from the lanthanides La through Lu, Y, Sc, In, Ca, and Mg with the balance zirconia (ZrO 2 ), hafnia (HfO 2 ), titania (TiO 2 ), or mixtures thereof. The second phases have a characteristic thickness (T 6 ) of less than 2.0 micrometers (μm). The spacing between second phases has a characteristic thickness (T 5 ) of less than 8.0 micrometers (μm).

The invention claimed is: 
     
       1. A process for coating a substrate with a ceramic thermal barrier coating, the substrate comprising an airfoil, the process comprising:
 generating a plume of ceramic deposition material from a first source and a second source; 
 alternating the composition of the plume by generating vapor from the first and second sources in an alternating manner; and 
 moving the substrate relative, to the first and second sources, wherein: 
 the moving of the substrate moves a given region of the substrate through the plume with a period greater than a duration of generation of the vapor plume from the second source; and the relative speed of the moving and the frequency of alternation of the composition of the vapor plume are effective to deposit a matrix with embedded second phase patches of the coating from the first source and second source, respectively. 
 
     
     
       2. The process of  claim 1  wherein:
 the moving consists of a single rotation. 
 
     
     
       3. The process of  claim 1  wherein:
 a duration of generation of the vapor plume from the first source is 400-5000% of said period; and 
 a duration of generation of the vapor plume from the second source is 30-99% of said period. 
 
     
     
       4. The process of  claim 1  wherein:
 the first source comprises a yttria stabilized zirconia; and 
 the second source comprises at least 40 mole percent of oxides having the formula Ln 2 O 3 , where Ln is selected from the lanthanide La through Lu, Y, Sc, In, Ca, and Mg. 
 
     
     
       5. The process of  claim 1  wherein:
 the first source comprises a yttria stabilized zirconia; and 
 the second source comprises at least 40 mole percent of oxides having the formula Ln 2 O 3 , where Ln is selected from the lanthanide La through Lu, Y, Sc, In, Ca, and Mg with the balance zirconia (ZrO 2 ), hafnia (HfO 2 ), titania (TiO 2 ), or mixtures thereof. 
 
     
     
       6. The process of  claim 1  wherein:
 the generating the plume of ceramic deposition material from the first source and the second source comprises electron beam vaporization of the first source and the second source. 
 
     
     
       7. The process of  claim 1  wherein:
 each of the second phase patches represents less than 85% of the surface area of the substrate. 
 
     
     
       8. The process of  claim 1  wherein:
 deposition material from the first source forms a matrix; 
 deposition material from the second source forms second phases embeded within the matrix. 
 
     
     
       9. The process of  claim 8  wherein:
 the second phases have a characteristic thickness (T 6 ) of less than 2.0 micrometers (μm); and 
 the spacing between second phases has a characteristic thickness (T 5 ) of less than 8.0 micrometers (μm). 
 
     
     
       10. The process of  claim 8  wherein:
 the matrix comprises a yttria stabilized zirconia; and 
 the second phases comprise at least 40 mole percent of oxides having the formula Ln 2 O 3 , where Ln is selected from the lanthanides La through Lu, Y, Sc, In, Ca, and Mg with the balance zirconia (ZrO 2 ), hafnia (HfO 2 ), titania (TiO 2 ), or mixtures thereof. 
 
     
     
       11. The process of  claim 8  wherein:
 the second phases have characteristic thickness (T 6 ) of 0.15-1.0 μm; and 
 a ratio of the second phases characteristic thickness (T 6 ) to the spacing (T 5 ) between second phases, thickness-wise, is between 1:3 and 1:4. 
 
     
     
       12. The process of  claim 8  wherein:
 the matrix with embedded second phases form a layer having a thickness (T 4 ) of at least 76 micrometers. 
 
     
     
       13. The process of  claim 8  wherein:
 the matrix with embedded second phases form a layer having a thickness (T 4 ) of 76-350 micrometers. 
 
     
     
       14. The process of  claim 8 , further comprising:
 applying a bondcoat; and 
 applying a first TBC layer between the bondcoat and the matrix. 
 
     
     
       15. The process of  claim 14 , wherein:
 the first TBC layer has a nominal composition differing from a composition of the matrix by the presence of one or more additives in a total amount of up to 1.0 weight percent. 
 
     
     
       16. The process of  claim 8  wherein:
 the characteristic thickness (T 6 ) of the second phases is 0.15-1.0 micrometers (μm), and 
 the characteristic thickness (T 5 ) of the spacing between second phases is 0.5-3.0 micrometers (μm). 
 
     
     
       17. The process of  claim 8 , further comprising:
 applying an additional coating layer with a homogeneous chemistry atop the matrix with embedded second phases. 
 
     
     
       18. The process of  claim 17  wherein:
 the additional coating layer is more resistant to attack by molten silicate deposits than is the matrix. 
 
     
     
       19. The process of  claim 8 , further comprising:
 applying an additional coating layer atop the matrix and comprising oxyapatite and/or garnet. 
 
     
     
       20. The process of  claim 8 , wherein:
 the matrix and second phases are in a layer of the thermal barrier coating system with thickness (T 4 ) wherein the second phases account for 5-20% of said layer by volume. 
 
     
     
       21. The process of  claim 1  wherein:
 the generating a plume of ceramic deposition material from the first source and the second source is via electron beam physical vapor deposition; and 
 the alternating of the composition comprises applying the electron beam to the first and second sources in an alternating manner comprising:
 a duration of applying the electron beam to the first source of 400-5000% of said period alternating with a duration of applying the electron beam to the second source of 30-99% of said period greater than a duration of generation of the vapor plume from the second source. 
 
 
     
     
       22. The process of  claim 1  wherein:
 the first source comprises a yttria stabilized zirconia. 
 
     
     
       23. A process for coating a substrate with a ceramic thermal barrier coating, the process comprising:
 generating a plume of ceramic deposition material from a first source and a second source; 
 alternating the composition of the plume by generating vapor from the first and second sources in an alternating manner; and 
 moving the substrate relative to the first and second sources, 
 
       wherein:
 the first source comprises a yttria stabilized zirconia; 
 the second source comprises at least 40 mole percent of oxides having the formula Ln 2 O 3 , where Ln is selected from the lanthanide La through Lu, Y, Sc, In, Ca, and Mg; 
 the moving of the substrate moves a given region of the substrate through the plume with a period greater than a duration of generation of the vapor plume from the second source; 
 deposition material from the first source forms a matrix; and 
 deposition material from the second source forms second phases embeded within the matrix. 
 
     
     
       24. A process for coating a substrate with a ceramic thermal barrier coating, the process comprising:
 generating a plume of ceramic deposition material from a first source and a second source; 
 alternating the composition of the plume by generating vapor from the first and second sources in an alternating manner; and 
 moving the substrate relative to the first and second sources, 
 
       wherein:
 deposition material from the first source forms a matrix; 
 deposition material from the second source forms second phases embeded within the matrix; 
 the moving of the substrate moves a given region of the substrate through the plume with a period greater than a duration of generation of the vapor plume from the second source; 
 the matrix comprises a yttria stabilized zirconia; and 
 the second phases comprise at least 40 mole percent of oxides having the formula Ln 2 O 3 , where Ln is selected from the lanthanides La through Lu, Y, Sc, In, Ca, and Mg with the balance zirconia (ZrO 2 ), hafnia (HfO 2 ), titania (TiO 2 ), or mixtures thereof. 
 
     
     
       25. A process for coating a substrate with a ceramic thermal barrier coating, the process comprising:
 generating a plume of ceramic deposition material from a first source and a second source; 
 alternating the composition of the plume by generating vapor from the first and second sources in an alternating manner; and 
 moving the substrate relative to the first and second sources, 
 
       wherein:
 deposition material from the first source forms a matrix; 
 deposition material from the second source forms second phases embeded within the matrix; 
 the moving of the substrate moves a given region of the substrate through the plume with a period greater than a duration of generation of the vapor plume from the second source; and 
 the method further comprises applying an additional coating layer atop the matrix and comprising oxyapatite and/or garnet. 
 
     
     
       26. A process for coating a substrate with a ceramic thermal barrier coating, the process comprising:
 generating a plume of ceramic deposition material from a first source and a second source; 
 alternating the composition of the plume by generating vapor from the first and second sources in an alternating manner; and 
 moving the substrate relative to the first and second sources, wherein: 
 a duration of generation of the vapor plume from the first source is 400-5000% of said period; and 
 a duration of generation of the vapor plume from the second source is 30-99% of said period.